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B. I'. CRABBS.

Mill for Grinding and Reducing. No. 229,589.

Patented July 6, 1880.

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t M/wl/WLM/ MPUERS, FHOTWLITHOGHAPNER. WABNINGIO"Y D. G.

UNITED STATES PATENT OFFICE.

BENJAMIN F. CRABBS, OF WASHINGTON, DISTRICT OF COLUMBIA.

MILL FOR GRINDING AND REDUCING.

SPECIFICATION forming part of Letters Patent No. 229,589, dated July 6, 1880.

Application filed April 7, 1880.

To all whom it may concern:

Be it known that I, BENJAMIN F. CRABBS, a citizen of the United States, residing at Washington, District of Columbia, have invented certain new and useful Improvements in Milling-Machines 5 and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in theart to which it appertains to make and use the same, reference being had to the accompanying drawings, and to letters or iigures of reference marked thereon, which form a part of this specication.

My invention relates to improvements in that class of milling-machines in which the grain is fed between a vertical revolving circular stone and a stationary concave that may be adjusted with reference to the circular stone in order that a fine or coarse quality of material may be produced from the substance passed through the mill.

My improvement consists of the mechanical devices used for the purpose of moving the concave laterally, whereby it may be brought near to or caused to recede from the circular stone uniformly; or, as more specically stated, it consists of Vvertically-adjustable guides, in combination with the means employed for sustaining the concave after being set up, by which. the relative positions ofthe faces of the stones may be regulated, if required, and the circumferential distance between the face of the concave and that of the circular stone sustained afterward, when the concave is raised or lowered vertically, either mechanically or from unavoidable causes.

The object of my invention is to supply such devices for the regulation of the 'concave in its relation to the circular stone as shall best accomplish the purpose for which the mill is designed'.

In order to enable others skilled in the art to which my invention appertains to make and use the same, I will now proceed to describe its construction and operation, referring to the accompanying drawings, which form a part of this specication, and in which- Figure l is a side elevation of a mill having my invention combined therewith, a portion. of the supporting frame-work being represented in broken lines. Fig. 2 is an end ele- (No model.)

vation of the same, showing a modification of one of the features of my invention.

Similar letters indicate like parts.

The letter A 4designates a frame-work, on which is mounted in suitable bearings the circular grinding-stone,V B, which is actuated in the usual manner.

C represents the concave, which rests on a cross-bar, t, of the frame A, and is held in position by two converging arms, a a', on each side, that pass through slots in the straps b b, which are iirmly attached to the concave C in any manner.

The arms a a have on their ends which pass through the strapsb b screw-threads, and are connected thereto by the .nuts b" and jamnuts b2. The said arms a a terminate in a cross-head, c, and pivoted to this cross-head c are connecting-rods e, which have cccentricstraps e at their ends, that encircle eccentrics f, formed on shaft g, which is journaled in bearings on the frame A opposite to that part which sustains the concave C.

On the shaft g is keyed the worm-wheel g', gearing with the worm h on a shaft, h', having bearings in the brackets h2, attached to or formed on frame A.

The end of the shaft h is provided with a hand-wheel, wuby which it may be turned.

On eachof the arms a a', adjacent tothe crosshead c, are rguides 61,61', bearing against extensions of the boxes la k, Fig.A 2, provided with elongated slots, Fig. 1, through which pass set-screws, that serve to keep the guides a. a' in position.

By means of the set-screws and slots it is evident that the said guides a a may be vertically adjusted, for reasons more fully hereinafter stated.

The standard-rods m m on the cross-bar t prevent a sideral displacement of the concave C.

In Fig. l ofthe drawings the stones B and C-are represented with their faces parallel, that position being, in my judgment, the best for the purpose of attaining the most satisfactory results in grinding with this class of mills.

lt is evident that the distance between the faces of the stones may be increased or di minished by turning the hand-wheelw through IOO the medium of the intervening parts connecting with the concave C after the concave C has been set up and been attached to the arms a a' by means of the nuts b and jam-nuts b2, with an equal pressure on both sides exerted at one and the same time.

The gages or guides d d', whose inner edges are parallel and rest on the extensions of the boxes k k, Figs. 1 and 2, serve to sustain the arms a a', cross-heads c, and connecting-rods e, and prevent them from moving vertically when properly secured to the arms a a. Consequently the relative position of the faces of the stones B and C will not be changed when the concave C is laterally adjusted.

The guides d d,when adjusted, as designed, so that the faces of the stones shall he parallel, as represented in Fig. l, are secured to the arms a a',so that their edges which bear against the extensions of the boxes k k are parallel to each other, as shown. [t is obvious, therefore, the laterally-adjusting mechanism being allowed to remain at rest. that if the concave U be raised, as represented in Fig. 1 by the broken lines, so as to come in contact with the circular stone B, the stones will not lose their parallelism when theyY have been set as stated with that relative position of their faces, and the same principle will hold when the distance between the faces ofthe stones, as shown, has been but one-half reduced; nor will the proportionate distance between the faces of the stones B and C be changed should the concave C have been set so that either its top or bottom was closest to the stone B if raised in a similar manner. 1t is manifest that a like result will be obtained if the concave C be lowered instead of raised, as shown. This peculiar-ity of my invention I consider a highly important feature in connection with mills of this class, for in grinding the concave may be depressed slightly, when an overcrowding of the mill occurs from any cause, by reason of a yielding of the frame-work, and were the stones not thus absolutely prevented from losing the perfect parallelism of their faces the top of the concave would be depressed upon the revolving circular stone and the grain or other material to be ground barred from entering between them, therebycausing the machine to become clogged.

A somewhat similar unsatisfactory e'ect is produced should the concave spring upward, and thus cause the bottom to come in contact with the circular stone, and in either case a poor result would be obtained from the machine in its operation compared to that attained from the use of my invention, which serves to maintain the parallelism of the faces of the stones under all ordinary circumstances in grinding when the concave has once been thus properly set.

The concave U may be mechanically raised or lowered vertically by means of a screw-stem, yn, Fig. 2, the upper end of which presses against a plate or socket, q, fastened to the bottom of the concave C, while its lower end is journaled in the cross-bar tof the frame A, and it may be operated by a hand-bar, o.

A shaft having cccentrics suitably arranged, similar to those on the shaft g, may be located beneath the concave C in a position correspending to that of the cross-bar t, and the said shaft, being ionrnaled in the frame A. may be, with its eccentrics, used to produce a like result to the stem-screw a, and also serve as a support for the concave C instead of the cross-bar t.

Either of the above-mentioned devices may be used in conjunction with the laterallyadjusting mechanism described, or separately, and will serve to produce similar results by causing the faces of the stones to approach or recede from each other.

Having thus described my invention, what I wish it to be understood that Iclaim as new, and desire to secure by Letters Patent, is-

In a vertical grinding-mill, the means employed for obtaining a lateral adjustment of the concave. consisting of the arms a a', cross head c, guides d d', connecting-rods e, eccentries f, shaft g, wormwheel g', and operatingworm h, all arranged and operating substantially as shown and described.

ln testimony whereof I have affixed my signature in presence of two witnesses.

BENJAMIN F. CRABBS.

Witnesses:

H. A. HALL, JAMES H. SMITH. 

